1. Field of the Invention
The present invention generally relates to the field of protection of rolled sheet materials. In particular, the present invention relates to a shielding device for the protection of the ends of such rolls during transportation and a method and apparatus for forming same.
2. Description of the Prior Art
Large heavy rolls of sheet material are often transported on vehicles from one place to another. These rolls are often bound with strapping through the core about the ends and over the exterior surface to retain their integrity during handling. When the rolls are loaded for transport, it is common to lay them on their exterior surface. The curvature of the exterior surface facilitates movement of the rolls on the loading deck. Further, when the rolls are lying on their exterior surface, loading cranes can insert a hook or bar into the hollow core to pick up the rolls. Once the rolls are located on the deck of a vehicle, stops are wedged under the exterior surface to prevent them from rolling. Finally the rolls may be fastened down with chains, or the like, that pass through the core and are secured to the deck at each end of the roll. The number of chains used to fasten the roll in place will depend upon the weight of the roll but it is common to have three or more chains that are secured forward, rearward and in line with the axis of the roll.
During transportation on a vehicle, rolls may be shaken and jostled. The securing chains resist movement by pulling in an opposite direction against the interior surface of the core particularly about the edges. Over a long journey frictional abrasion between the rolls and the chains can cause gouging, bending and deformation due to chain tension and other damage that affects one or more layers of the rolled material from the interior surface outwards. In severe cases, there may also be telescoping of the roll where adjacent layers of the rolled material slide against one another in the direction of the axis of the roll. Telescoping can expose greater areas to damage from the chains, expose more material to the elements and create handling problems. Consequently, when the roll is finally unrolled and put into use, there is often a portion of the sheet metal along the edges which is unusable due to damage from the chains. Further to this end, as both edges typically suffer damage during transportation, the usable width of the roll is decreased from both edges and requires the additional labour of trimming the damaged edges. This situation often results in unnecessary waste of material and typically drives the price of products fabricated from such rolled material up due to the waste factor. When the rolled material is of poorer quality such as mild carbon steel, or the thickness of the rolled stock is such that it resists damage, the consequences of the edge damage are not as severe. However, when the rolled stock comprises significantly more expensive material such as stainless steel or aluminum or is relatively thin such as gauge sheet material, the costs associated with such damage can be significant.
In the prior art a number of attempts have been made to reduce the damage to rolls from chains. One prior art device is a large metal ring or pipe section which is fitted into the core about the edges. The chains are then led through the rings and are thus separated from the edges and held above the interior surface to protect same from chain abrasion. These large metal rings suffer the disadvantage that they must be manufactured to the correct size to fit into the core of a roll. However, core diameters may be different for different sheet materials, different material thicknesses etc., and, even if these parameters are constant, there may be a wide tolerance in the core diameter from roll to roll as a result of the rolling process. Consequently, a manufacturer of such rings must make many sizes, thereby increasing costs and inventory. The rings are cumbersome to use and store and the fit may be imperfect in spite of the manufacturer's efforts. Furthermore, steel rings are heavy for trackers to install and can cause back injuries, are prone to corrosion and are difficult to store.
The problem of the rings has been addressed by partial shields which encircle only part of the circumference of the edges of the core. All such partial shields known to the inventor are manufactured from metal in order to withstand the severe stresses and high bearing forces of the chains required to secure large rolls. These metal partial shields are relatively rigid and therefore do not readily conform to the size of the interior surface of the core. Being metal of sufficient thickness to withstand the chain abrasion, such shields are also capable of cutting or injuring an operator if dropped or mishandled.
When loaded, the protector elastically deforms to conform to the shape of the core and interior edge. In contrast to using conventional metal protectors, the steel roll itself will deform under the loading forces as the protectors are typically formed of plate steel which is thicker and thereby less elastic than the sheet forming the steel roll.